Polish pad, polish method, and method manufacturing polish pad

ABSTRACT

A polish pad including a polish region contributing to polishing of a polish object; and a polish layer being disposed in the polish region and including unfoamed segments comprising unfoamed resin and foamed segments comprising resin including independent pores. The unfoamed segments and the foamed segments of the polish layer are made of the same raw resin.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2013-108923, filed on, May 23, 2013 the entire contents of which are incorporated herein by reference.

FIELD

Embodiments disclosed herein generally relate to a polish pad, a polish method, and a method of manufacturing the polish pad.

BACKGROUND

In the technical field of semiconductor manufacturing, chemical mechanical polishing (CMP) is indispensable in the polishing of interlayer insulating film, formation of element isolation regions, formation of plugs, and formation of embedded metal interconnects.

In general, a rotary-type CMP apparatus polishes the polish object by rotating the polish head and the table simultaneously while placing the polish object in contact with the polish pad and supplying slurry onto the polish pad.

Because the polish pad contacts the polish object during polishing, the hardness and the capacity to retain the slurry of the polish pad greatly influence the resulting planarity which may be evaluated by the presence/absence of defects, by the polish rate, and by the evenness of the polishing.

Various types of resins may be used in the polish layer of the polish pad. A hard polish layer provides high planarization capacity but exhibits low conformability to the undulations of the wafer or to the global steps of the polish object and may leave unpolished film(s) or cause unevenness in the thickness of the remaining film(s). In contrast, a soft polish layer is deformation prone and exhibits good conformability to the undulations of the wafer or the global steps of the polish object, but provides lower planarization capacity compared to the hard polish layer. Because the soft polish layer is deformation prone, the outermost peripheral portion of the polish pad may become deformed and cause excessive polishing.

A polish pad is being proposed which the polishing layer comprises a double layer. One example of such double-layered polish pad is formed of a resin sheet including a soft resin and a hard resin. The soft resin and the hard resin are soluble to the same solvent.

The resin sheet further includes an agglomerate resin having multiplicity of interconnected micro-pores. The agglomerate resin, having an average diameter which is greater than the average diameter of the micro-pores, is evenly distributed in the resin sheet.

The polish pad is deformation prone at the outer edge of the semiconductor wafer. Conventionally, agglomerate resin was less than 200 μm in size and thus, was not able to inhibit the deformation of the polish pad at the outer edge of the semiconductor wafer.

Because of the recent demands for dramatic improvement in microfabrication of memory devices, the planar dimension of the wafer is reaching its scaling limit. Thus, 3D memory is being developed in which elements are stacked vertically with respect to the wafer surface. The manufacturing process flow of the 3D memory produces a large step in the level of few μm in the vertical direction after the elements have been stacked. Thus, the step needs to be removed with high planarizing capacity and high polish rate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate a first embodiment where FIG. 1A is one example of an exterior view of a polishing apparatus and FIG. 1B illustrates an example of a region of a polish pad which contributes in the polishing.

FIG. 2 pertains to the first embodiment and illustrates one example of a cross section of a polish layer of a polish pad.

FIG. 3 pertains to the first embodiment and illustrates one example of a cross section of the polish pad.

FIG. 4 pertains to the first embodiment and illustrates one schematic example of a manufacturing process flow of the polish pad.

FIG. 5 pertains to the first embodiment and illustrates one schematic example of a cross section of a polish object before being polished.

FIG. 6 pertains to the first embodiment and illustrates one schematic example of a cross section of the polish object after being polished.

FIGS. 7 and 8 each pertains to the first embodiment and each illustrates one schematic example of a cross section of the polish object being polished.

FIGS. 9 and 10 each pertains to the first embodiment and each illustrates one schematic example of a cross section of an undulated semiconductor wafer covered with an insulating film having gradual recesses which is to be polished.

FIG. 11 pertains to the first embodiment and illustrates one schematic example of how a polish pad contacts the outermost peripheral portion of the semiconductor wafer when the polish object is polished by a polish pad comprising an unfoamed resin.

FIG. 12 pertains to the first embodiment and illustrates one schematic example of how a polish pad contacts the outermost peripheral portion of the semiconductor wafer when the polish object is polished by a polish pad comprising a foamed resin.

FIG. 13 pertains to the first embodiment and illustrates one schematic example of how a polish pad contacts the outermost peripheral portion of the semiconductor wafer when the polish object is polished by a polish pad including the foamed segment and the unfoamed segment.

FIG. 14 pertains to a second embodiment and corresponds to FIG. 2.

FIGS. 15 and 16 each pertains to the second embodiment and each illustrates one example of a cross section of a polish pad.

FIGS. 17A, 17B, 17C, 17D, 17E, and 17F pertain to the second embodiment and illustrate one example of a manufacturing process flow of the polish pad.

FIG. 18 pertains to the second embodiment and corresponds to FIG. 13.

FIGS. 19, 20, 21, 22, 23, and 24 pertain to a third embodiment and illustrate schematic examples of planar layouts of the foamed segments and the unfoamed segments.

FIGS. 25, 26, and 27 pertain to the fourth embodiment and illustrate schematic examples of planar layouts of trenches formed in the polish layer of the polish pad.

DESCRIPTION

In one embodiment, a polish pad is disclosed. The polish pad includes a polish region contributing to polishing of a polish object; and a polish layer being disposed in the polish region and including unfoamed segments comprising unfoamed resin and foamed segments comprising resin including independent pores. The unfoamed segments and the foamed segments of the polish layer are made of the same raw resin.

Embodiments

Embodiments are described hereinafter with references to the accompanying drawings. Elements that are identical or similar across the embodiments are identified with identical or similar reference symbols and may not be re-described. The description will focus on the features of each embodiment. In the following description, the terms “top surface” and “upper surface” are used in the same or similar meaning and the terms “under surface” and “lower surface” are used in the same or similar meaning.

First Embodiment

FIG. 1A is one schematic example of an external view of a polishing apparatus. Polishing apparatus 1 includes rotary table 2, rotary shaft 3, polish pad 4, and polish head 5. Rotary table 2 is provided on rotary shaft 3. Rotary table 2 is rotated in a predetermined speed when rotary shaft 3 is driven in rotation by an external drive unit not shown.

Polish head 5 holds the polish object, in this case, semiconductor wafer 6 in the lowermost portion thereof. Semiconductor wafer 6 is retained by polish head 5 so that the polish surface faces polish pad 4.

Polish head 5 includes air bag mechanism 7, retainer ring 8, and rotary shaft 9. Air bag mechanism 7 is capable of pressing semiconductor wafer 6 against rotary table 2. Retainer ring 8 prevents semiconductor wafer 6 from falling off toward the outer peripheral side during polishing. Polish head 5 is eccentric with respect to the center of rotary shaft 3 of rotary table 2 and is vertically and horizontally movable. Polish head 5 is further capable of rotating about rotary shaft 9.

Above rotary table 2, nozzle 11 is disposed for dispensing slurry 10. Nozzle 11 is disposed straight above rotary shaft 3 and centered on rotary table 2 in FIG. 1A. However, nozzle 11 need not be centered on rotary table 2 and may be de-centered. Slurry 10 comprises, for example, abrasive grains of cerium dioxide.

When polishing, slurry 10 is dispensed onto polish pad 4 from nozzle 11 and polish head 5 is lowered so as to place semiconductor wafer 6 in contact with polish pad 4. Then, rotary table 2 and polish head 5 are rotated in the same direction about rotary shaft 3 and rotary shaft 9, respectively. At this instance, semiconductor wafer 6 is polished by being pressed against rotary table 2 by the pressure applied by air bag mechanism 7.

FIG. 1B indicates region R1 of polish pad 4 in which semiconductor wafer 6 is moved during the polishing process. Region R1 is an annular region centering on center C. Region R1 of polish pad 4 contributes in the polishing of semiconductor wafer 6.

Polishing apparatus 1 is further provided with dressing mechanism 12 for teething polish pad 4. On one end of dressing mechanism 12, dresser 13 is disposed. Dresser 13 comprises multiplicity of abrasive grains of diamond.

Dressing mechanism 12 teethes polish pad 4 by rotating and swinging dresser 13 during or before/after the polishing of semiconductor wafer 6. By providing dressing mechanism 12 it is possible to evenly teeth the surface of region R1 in which semiconductor wafer 6 is moved.

For example, rotation speed of rotary table 2 may be 100 rpm and rotation speed of polish head 5 may be 103 rpm. A pressure of 400 hPa may be applied to semiconductor wafer 6 when polishing semiconductor wafer 6.

FIG. 2 illustrates one schematic example of a cross section of polish pad 14. Polish pad 14 illustrating in FIG. 2 is made of a single layer of polish layer 22. Polish layer 22 comprises foamed segment 24 and unfoamed segment 25. Foamed segment 24 is provided with micro-pores 23 being independent of one another, whereas unfoamed segment 25 has no micro-pores 23. Though only partially shown in FIG. 2, foamed segment 24 and unfoamed segment 25 are randomly disposed.

Micro-pores 23 in foamed segment 24 are preferably 300 μm or less in diameter. The hardness and the planarization capacity of polish layer decrease with the increase in the volume of micro-pores 23. On the other hand, the capacity to retain slurry 10 and the polish rate increase with the increase in the surface area of micro-pores 23 formed on the surface of polish layer 22. In order to increase the rate of the surface area of polish layer 22 to the volume of polish layer 22, it is preferable to set the diameter of micro-pores 23 to 300 μm or less.

FIG. 3 is another schematic example of a cross section of a polish pad. Polish pad 26 illustrated in FIG. 3 is provided with polish layer 22 shown in FIG. 2 and cushion layer 27 in intimate contact with the under surface of polish layer 22. Cushion layer 27, may comprise, for example, a polyurethane foam, a polyethylene foam, or unwoven fabric.

The first embodiment will be described through the use of polish pad 14 shown in FIG. 2. Foamed segment 24 and unfoamed segment 25 of polish layer 22 need to be made of the same resin.

This is because the difference in the material of foamed segment 24 and unfoamed segment 25 produces a difference in the cut rate of foamed segment 24 and unfoamed segment 25 when teething polish pad 14. The difference in the cut rate produces a step at the interface of foamed segment 24 and unfoamed segment 25 and the recessed region resulting from the step does not contribute in the polishing. This is why foamed segment 24 and unfoamed segment 25 need to be made of the same material in the first embodiment. In the first embodiment, foamed segment 24 and unfoamed segment 25 may be made of a polyurethane resin or an epoxy resin for example.

Polish layer 22 may be made by the manufacturing process flow shown in FIG. 4. First, polyurethane resin 28, for example, is prepared as raw resin 28. Micro-balloon 29 provided with micro-pores is mixed with raw resin 28 to obtain a foamed pellet 30 formed into a cuboid shape, for example, as shown in A of FIG. 4. In forming foamed pellet 30, raw resin 28 may be mixed with gas instead of micro-balloon 29.

Unfoamed pellet 31 which is not mixed with micro-balloon 29 is formed into a cuboid shape, for example, as shown in B of FIG. 4. Foamed pellet 30 and unfoamed pellet 31 are randomly inserted into mold 32 having enclosed bottom as shown in C of FIG. 4. Foamed pellet 30 and unfoamed pellet 31 within mold 32 are thermally cast as shown in D of FIG. 4. Polish layer 22 is formed by the above described process flow. Polish layer 22 may be formed so that foamed segment 24 and unfoamed segment 25 are disposed at random. Average diameter of the micro-pores in the foamed segment 24 may be configured to, for example, 50 μm.

As will be later exemplified in a fourth embodiment, trenches 80 (corresponding to a retaining pattern such as lattice trenches) or through holes are formed throughout the surface of polish layer 22 of polish pad 14. Trenches 80 or through holes are provided for spreading or retaining slurry 10 on the surface of polish pad 14.

FIG. 5 schematically illustrates one example of a cross section of a polish surface of semiconductor wafer 6. As shown in FIG. 5, 3 dimensional (3D) memory elements 41 are disposed above semiconductor substrate 40. Insulating film 42 is further disposed above 3D memory elements 41. 3D memory element 41 comprises a stack of multiplicity of memory element layers. 3D memory element 41 is formed into a substantially trapezoidal shape which becomes narrower toward the top. Insulating film 42 is filled between groups of 3D memory elements 41. When insulating film 42 is filled at some level of thickness, step H is generated which is, by principle, equivalent to the height of 3D memory element 41.

After filling insulating film 42, interconnects are formed above insulating film 42. Because the formation of interconnects involves lithography and etching, step H may cause problems such as defocusing. Thus, step H is substantially reduced to 0 (zero) by planarizing the upper surface of insulating film 42 as shown in FIG. 6 by polishing.

In the first embodiment, a step of few micrometers (μm), for example, 2 μm may exist in the underlying layer when 3D memory element 41 is formed. Insulating film 42 of few micrometers (μm) of, for example, 3 μm is disposed above the step. Semiconductor wafer 6 structured as described above is planarized by polishing.

The diameters of foamed segment 24 and unfoamed segment 25 may be adjusted by varying the size of the aforementioned foamed pellet 30 and unfoamed pellet 31. Further, it is possible to obtain the target polish properties through adjustment of the ratio of foamed segment 24 and unfoamed segment 25. For instance, the ratio of volume of unfoamed segment 25 relative to the volume of foamed segment 24 may be increased for further improvement of planarity.

Next a description will be given on the polishing of local protrusion 43 originating from 3D memory element 41 as shown in FIGS. 7 and 8. In FIGS. 7 and 8, local protrusion 43 of insulating film 42 is oriented downward in order to illustrate the actual orientation in which polishing is carried out. FIG. 7 exemplifies local protrusion 43 being surface polished by foamed segment 24. FIG. 8 exemplifies local protrusion 43 being surface polished by unfoamed segment 25.

Polish layer 22 of polish pad 14 includes foamed segment 24 and unfoamed segment 25 disposed at random. Thus, as shown in FIGS. 7 and 8, the polishing progresses with local protrusion 43 moving alternately over/passed foamed segment 24 and unfoamed segment 25. In the actual polishing, the states illustrated in FIGS. 7 and 8 are repeated.

As shown in FIG. 7, because foamed segment 24 is soft, local protrusion 43 is easily embedded into a portion of an upper surface of foamed segment 24 when local protrusion 43 moves over foamed segment 24. Thus, foamed segment 24 conforms to the surface profile of local protrusion 43 and reduces the difference in the pressure applied to local protrusion 43 and the pressure applied to other portions.

In contrast, because unfoamed segment 25 is hard, unfoamed segment 25 does not easily conform to the surface profile of local protrusion 43 when local protrusion 43 moves over unfoamed segment 25 as shown in FIG. 8. Because the post-polish surface planarity of local protrusion 43 is determined by the planarization performance achievable when the greatest planarization capacity is being exerted during the polishing, it is possible to obtain a high level of planarization performance substantially equal to the planarization performance of a polish pad being made of only unfoamed segment when polish pad 14 having polish layer 22 of the first embodiment is used.

FIGS. 9 and 10 each illustrate, by way of example, how a gradual recess 47, formed into insulating film 46 disposed over undulation 45 of semiconductor wafer 6, and the periphery of recess 47 are polished by polish layer 22 of polish pad 14. In portions located over steps of the underlying structure such as undulation 45, the post-polish film needs to have constant thickness.

FIG. 9 shows recess 47 of insulating film 46 conforming to undulation 45 and the periphery of recess 47 being surface polished by foamed segment 24. FIG. 10 shows recess 47 of insulating film 46 conforming to undulation 45 and the periphery of recess 47 being surface polished by unfoamed segment 25. In the actual polishing, the polishing states illustrated in FIGS. 9 and 10 are repeated. In FIGS. 9 and 10, undulation 45 of insulating film 46 is oriented downward in order to illustrate the actual orientation in which polishing is carried out.

Unfoamed segment 25 does not easily conform to recess 47 when undulation 45 moves over unfoamed segment 25 to polish the periphery of recess 47 formed into insulating film 46 as shown in FIG. 10. Thus, the pressure applied to recess 47 becomes smaller than the pressure applied to other portions which results in reduced polish speed.

In contrast, foamed segment 24 easily conforms to the gradual recess 47 as shown in FIG. 9. As a result, the pressure applied to recess 47 is increased and it becomes possible to reduce the difference in the pressure applied to recess 47 and the pressure applied to other portions. The use of polish pad 14 including polish layer 22 of the first embodiment improves the evenness of the thickness of the post-polish film compared to the use of a polish pad being made of only unfoamed resin even in the presence of a step in the underlying structure such as undulation 45.

Under specific conditions, the length of undulation 45 of semiconductor substrate 40 may measure 1 [mm] or greater. Thus, when the minor axis of foamed segment 24 is short, sufficient conformity to undulation 45 of semiconductor substrate 40 may not be achieved. In such case, the minor axis of foamed segment 24 of polish layer 22 is preferably 1 [mm] or greater.

FIG. 11 shows one example of a comparison of polish pad 105 made of unfoamed resin and the outermost edge of semiconductor wafer 50 disposed above polish pad 105. FIG. 12 shows one example of a comparison of polish pad 104 made of foamed resin and the outermost edge of semiconductor wafer 50 disposed above polish pad 104. FIG. 13 shows one example of a deformed polish pad 14 contacting the outermost periphery of semiconductor wafer 50.

The upper surface of the outer edge of semiconductor wafer 50 (corresponding to the under surface of semiconductor wafer 50 in FIGS. 11 to 13) is chamfered. Above the central upper surface of semiconductor wafer 50 (corresponding to the under surface of semiconductor wafer 50 in FIGS. 11 to 13), pattern 51 is formed. Edge cut boundary 52 of pattern 51 is located on the outer edge of semiconductor wafer 50.

When polish pad 105 made of unfoamed resin shown in FIG. 11 is used, excessive polishing does not easily occur. This is because polish pad 105, being hard, deforms only slightly at edge cut boundary 52 of pattern 51 and pressure is applied only from the downward direction as viewed in FIG. 11.

When polish pad 104 made of foamed resin shown in FIG. 12 is used, polish pad 104 deforms significantly by the contraction of its internal pores which causes semiconductor wafer 50 to plunge into polish pad 104. As a result, lateral pressure is applied to edge cut boundary 52 of pattern 51 in addition to the pressure applied from the downward direction as viewed in FIG. 11 and this promotes excessive polishing.

Excessive polishing occurring at edge cut boundary 52 causes exposure of the silicon substrate in unintended regions and destructions of patterns near edge cut boundary 52 which in turn produces sources of dust. The use of polish pad 14 including polish layer 22 of the first embodiment shown in FIG. 13 reduces deformation of polish pad 14 at edge cut boundary 52 compared to the use of polish pad 104. Thus, it is possible to inhibit excessive polishing.

The polish rate relies on the amount of slurry 10 retained on the surface of polish pad 14. The amount of slurry 10 retained relies on the surface area of polish pad 14. The surface area of polish pad 104 formed of foamed resin is increased by the pores opened at the surface of polish pad 104. Thus, polish pad 104 retains greater amount of slurry 10 and consequently exhibits higher polish rate as compared to polish pad 105 made of unfoamed resin.

A summary of the first embodiment is given below.

When polishing local protrusion 43 with polish pad 14, foamed segment 24 easily conforms to the surface of local protrusion 43 but unfoamed segment 25 does not easily conform to the surface of local protrusion 43. The post-polish surface planarity of local protrusion 43 being polished by polish pad 14 having polish layer 22 is determined by the planarization performance achievable when the greatest planarization capacity is being exerted during the polishing. Thus, it is possible to obtain a high level of planarization performance substantially equal to the planarization performance of a polish pad being made of unfoamed segment 25 when polish pad 14 is used.

When moving over a step of the underlying structure spanning over a wide area, such as undulation 45 of semiconductor substrate 40, foamed segment 24 of polish pad 14 is capable of conforming to the step by deformation. Thus, when polish pad 14 is used, it is possible to reduce unpolished films and improve the evenness of the thickness of the post-polish films. Foamed segment 24 is capable of retaining slurry 10 and thus, polish rate can be improved as compared to a polish pad formed solely of unfoamed resin.

Further, because polish layer 22 is provided with unfoamed segment 25, it is possible to suppress amount of deformation of polish pad 14 responsive to the load applied by semiconductor wafer 6. As a result, excessive polish originating from deformation at the outermost periphery of semiconductor wafer 6 can be suppressed.

By using polish pad 14 including both foamed segment 24 and unformed segment 25, high level of planarity and evenness in the thickness of the post-polish film can be obtained as well as achieving a high polish rate and high productivity.

Hardness of polish layer 22 is determined, for example, by the hardness of the raw resin itself and the volume percentage of independent micro-pores 23 and thus, may be controlled to the target hardness through adjustment of these conditions. When target properties cannot be obtained by the use of a single polish pad, multiple types of polish pad may be used in multiple polish processes, which leads to an increase in the number of process steps. In the first embodiment, it is possible to complete the polishing process with a single type of polish pad 14.

For example, as shown in FIG. 5, minor axis of unfoamed segment 25 is preferably controlled to range from 1 [mm] to 10 [cm] when planarizing insulating film 42 disposed above 3D memory element 41. The minor axis indicates the shortest axis of unfoamed segment 25 in plan view. Because the capacity of unfoamed segment 25 to retain slurry 10 is weak, slurry 10 is supplied to unfoamed segment 25 from adjacent foamed segment 24. When the minor axis of the cuboid unfoamed segment 25 is relatively long, polish rate deteriorates because the amount of slurry 10 retained in the central portion of unfoamed segment 25 is insufficient. The planar structural length of 3D memory element 41, in some cases, may be sized to 1 [mm] or greater. In such case, the minor axis of the cuboid unfoamed segment 25 is preferably controlled from 1 [mm] to 10 [cm] in order to sufficiently planarize surface step H indicated in FIG. 5.

Second Embodiment

FIGS. 14 to 18 illustrate a second embodiment which differs from the first embodiment in that the unfoamed segment is formed continuously from the upper surface side to the under surface side and in that the unfoamed segment is disposed alternately in plan view.

Polish pad 60 illustrated in FIG. 14 includes polish layer 61. Polish layer 61 comprises foamed segment 63 and unfoamed segment 64. Foamed segment 63 is provided with micro-pores 62 independent of one another, whereas unfoamed segment 64 has no micro-pores 62. Foamed segment 63 corresponds to foamed segment 24 and unfoamed segment 64 corresponds to unfoamed segment 25.

Foamed segment 63 is similar to foamed segment 24 in that it contains multiplicity of independent micro-pores 62, but differs from foamed segment 24 in that foamed segment 63 exist continuously from the upper surface side to the under surface side of polish layer 61 and in that foamed segment 63 is disposed more sparsely compared to foamed segment 24. The average diameter of the micro-pores 62 contained in foamed segment 63 may measure, for example, 50 μm.

FIG. 15 illustrates one example of a polish pad. Polish pad 65 includes polish layer 61 shown in FIG. 14 and cushion layer 66 disposed below polish layer 61. Cushion layer 66 corresponds to cushion layer 27 of the first embodiment.

FIG. 16 is a schematic cross sectional view of another example of a polish pad. Polish pad 67 includes polish layer 61 illustrated in FIG. 14 and additional unfoamed segment 64 extending integrally and continuously along the undersides of foamed segment 69 and unfoamed segment 64 of polish layer 61.

Stated differently, polish pad 67 is structured such that in the upper surface side, foamed segment 63 and unfoamed segment 64 are exposed alternately, whereas in the under surface side, unfoamed segment 64 is exposed. In other words, foamed segment 63 may be formed discontinuously from the upper surface side to the under surface side as shown in FIG. 16.

Polish layer 61 can be manufactured by the manufacturing process flow illustrated, for example, in FIGS. 17A to 17F. As shown in FIG. 17A, micro-balloon is mixed with raw resin such as polyurethane resin or epoxy resin to obtain a foamed raw resin 68 having micro-pores 62. Foamed raw resin 68 is introduced into enclosed bottom container 69.

As shown in FIG. 17B, element 70 having preformed micro-trenches 70 a is pressed into foamed raw resin 68 from the upward direction and thermally molded. As a result, homogenous mold 71 having trenches 71 a is obtained as shown in FIG. 17C.

As shown in FIG. 17D, unfoamed raw resin 72 which is not provided with micro-pores 62 is introduced onto homogenous mold 71. As a result, unfoamed raw resin 72 is introduced into trenches 71 a. Then, the resulting structure is thermally molded with enclosed-bottom container 73 free of trenches to obtain composite mold 74 shown in FIG. 17E.

As shown in FIG. 17F, the upper and under surfaces of composite mold 74 is polished and/or cut until foamed segment 63 and unfoamed segment 64 are exposed alternately in both the upper and the under surfaces. As a result, polish layer 61 described earlier is obtained.

In the above described manufacturing process flow, unfoamed raw resin 72 is introduced into trenches formed into foamed raw resin 68. An opposite approach may be taken alternatively in which a homogenous mold having trenches is formed using unfoamed raw resin 72, whereafter foamed raw resin 68 is introduced into the trenches and thermally molded to obtain a composite mold.

In the above described manufacturing process flow, trenches 71 a of homogenous mold 71 was thermally die-molded using enclosed bottom container 69 and element 70 having preformed trenches 70 a. Alternatively, trenches 71 a may be formed by cutting. Foamed raw resin 68 in which micro-balloon was mixed with raw resin may be formed alternatively by mixing gas or foaming agent with raw resin. As will be later described in a fourth embodiment, trenches 80, one example of which may be lattice trenches, may be formed throughout the surface of polish layer 61 of polish pad 60 in order to supply and retain slurry 10 throughout the surface of polish pad 60.

FIG. 18 illustrates the deformation of polish layer 61 at the outermost periphery of polish pad 60. Because unfoamed segment 64 extends continuously from the upper surface to the under surface of polish layer 61, polish layer 61 does not deform easily even when semiconductor wafer 50 is pressed against polish layer 61. More specifically, unfoamed segment 64 serves as a reinforcement to inhibit plunging of semiconductor wafer 50 into polish layer 61 and consequently inhibit deformation of polish layer 61. Thus, excessive polishing of pattern 51 at edge cut boundary 52 can be inhibited effectively even when compared with polish layer 22 of polish pad 14 illustrated in FIG. 13 of the first embodiment.

As described above, polish layer 61 of the second embodiment is provided with foamed segment 63 and unfoamed segment 64 and exists continuously from the upper surface (top surface) to the under surface (bottom surface) at least in a portion of polish layer 61 in plan view. By using polish pad 60 having polish layer 61 disposed on its upper surface (top surface) side, it is possible to inhibit deformation of polish layer during the polishing and inhibit excessive polishing at edge cut boundary 52 of pattern 51.

Third Embodiment

FIGS. 19 to 24 illustrate a third embodiment. The third embodiment provides examples of how foamed segment 63 and unfoamed segment 64 maybe disposed in plan view when polish layer 61 is formed of foamed segment 63 and unfoamed segment 64 which extend from the upper surface to the under surface of polish layer 61 as was the case in the second embodiment.

As shown in FIG. 1A, polish head 5 rotates about rotary shaft 9 and further revolves around rotary shaft 3 of rotary table 2. Thus, region R1 in which semiconductor wafer 6 moves during the polishing process is an annular region located between first radius D1 and second radius D2 (> first radius D1) taken from center C as indicated in FIGS. 19 to 24.

In the example illustrated in FIG. 19, unfoamed segments 64 are arranged in a lattice and foamed segments 63 are embedded between unfoamed segments 64. Stated differently, foamed segments 63 are disposed as square dots and unfoamed segments 64 are embedded between foamed segments 63.

In the example illustrated in FIG. 20, unfoamed segments 64 are disposed as concentric rings each disposed from center C by different distances and foamed segments 63 are embedded between unfoamed segments 64.

In the example illustrated in FIG. 21, unfoamed segments 64 are disposed radially from the central portion to the outermost peripheral portion of polish layer 61 and foamed segments 63 are embedded between unfoamed segments 64.

In the example shown in FIG. 22, unfoamed segments 64 are disposed as square dots isolated from one another and foamed segments 63 are embedded between unfoamed segments 64. Stated differently, foamed segments 63 are arranged in a lattice and unfoamed segments 64 are embedded between foamed segments 63.

In the example shown in FIG. 23, unfoamed segments 64 are disposed as round dots isolated from one another and foamed segments 63 are embedded between unfoamed segments 64. In the example shown in FIG. 24, unfoamed segments 64 are embedded within sectors having a predetermined central angle about center C and foamed segments 63 are embedded between unfoamed segments 64. The layouts of segments 63 and 64 are not limited to those exemplified in FIGS. 19 to 24.

The examples described above are preferably arranged so that the percentage of foamed segment 63 and unfoamed segment 64 moving over any given region of semiconductor wafer 6 is substantially equal during the polishing process. This is because semiconductor wafer 6 exhibits different polish rates and planarization capacities when semiconductor wafer 6 is moving over foamed segment 63 and when semiconductor wafer 6 is moving over unfoamed segment 64.

In this respect, the lattice arrangement of FIG. 19, the square dot arrangement of FIG. 22, or the round dot arrangement of FIG. 23 are preferred among the layouts illustrated in FIG. 19 to 24. As a result, it is possible to substantially equalize the percentage of foamed segment 63 and unfoamed segment 64 moving over any given region of semiconductor wafer 6 and realize more ideal polishing process.

In the third embodiment described above, it is possible to make the polish rates and the planaraizing capacities within the surface of semiconductor wafer 6 to be substantially equal by the disposing foamed segment 63 and unfoamed segment 64 in the layout patterns described above. As a result, it is possible to improve the evenness of semiconductor wafer 6.

This is especially true when the percentage of foamed segment 63 and unfoamed segment 64 moving over any given region of semiconductor wafer 6 is substantially equal during the polishing process.

Fourth Embodiment

FIGS. 25 to 27 illustrate a fourth embodiment. The fourth embodiment provides examples of how trenches may be disposed in the surface of the polish layer of the polish pad in plan view.

Polish pads 4, 14, 26, 60, and 65 of the foregoing embodiments are provided with trenches 80 which are formed throughout the surface of polish layers 22 and 61, and which serve as a pattern for retaining slurry 10, etc. Description is given hereinafter through an example of polish layer 61 of polish pad 60. Trench 80 serves as a trench for supplying or retaining slurry 10 in the surface of polish pad 60. Thus, trenches 80 are preferably formed uniformly and evenly in both foamed segment 63 and unfoamed segment 64.

In the regions where trenches 80 are formed, polish pad 60 does not contact the surface of semiconductor wafer 6. Thus, when greater amount of trenches 80 are formed in either of foamed segment 63 and unfoamed segment 64, polishing performed on the segment (segment 63 or 64) having greater amount of trenches becomes less effective as compared to the polishing performed on the remaining other segment.

As a result, the percentage of contribution to the polishing process becomes greater in either segment 63 or 64 and therefore makes it difficult to obtain the target polish properties. Thus, trenches 80 are preferably formed evenly to cover the same amount of area in foamed segment 63 and in unfoamed segment 64.

FIGS. 25 to 27 schematically illustrate the examples of how trenches 80 maybe disposed. From the aforementioned perspective, the arrangement (such as lattice arrangement and square dot arrangement) of foamed segment 63 and unfoamed segment 64 are preferably different form the arrangement (such as concentric ring arrangement) of trenches 80 as shown in FIG. 25.

As shown in FIG. 26, when trenches 80 are arranged in the same or similar pattern to the pattern (such as lattice arrangement and square dot arrangement) of unfoamed segment 64 (or foamed segment 63), the pattern of unfoamed segment 64 may be disposed at pitch P1 and the pattern of trench 80 may be disposed at pitch P2 which differ from one another.

As shown in FIG. 27, when trenches 80 are arranged in the same or similar pattern to the pattern (such as lattice arrangement and square dot arrangement) of unfoamed segment 64 (or foamed segment 63), the angle of lattice of unfoamed segment 64 and the angle of lattice of trenches 80 may differ (inclination θ=45 degrees) from one another.

When trenches 80 are arranged as shown in FIGS. 25 to 27, trenches 80 are evenly distributed in foamed segment 63 and in unfoamed segment 64, and thus, it is possible to substantially equate the ratio of area occupied by trenches 80 in foamed segment 63 and in unfoamed segment 64 with the ratio of area occupied by segments 63 and 64 within the entire polish layer. As a result, it is possible to evenly distribute trenches 80 throughout the polish layer. Trenches 80 may be formed by cutting. Trenches 80 may be replaced by through holes, or both trenches 80 and through holes may be provided.

In such case, the ratio of area occupied by unfoamed segment 64 and foamed segment 63 in the region for disposing trenches 80 and/or through holes is preferably equated with the ratio of area occupied by segments 63 and 64 within the entire polish layer.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. 

What is claimed is:
 1. A polish pad comprising: a polish region contributing to polishing of a polish object; and a polish layer being disposed in the polish region and including unfoamed segments comprising unfoamed resin and foamed segments comprising resin including independent pores; wherein the unfoamed segments and the foamed segments of the polish layer are made of the same raw resin.
 2. The polish pad according to claim 1, wherein the unfoamed segments and the foamed segments are disposed at random.
 3. The polish pad according to claim 1, wherein the raw resin comprises a polyurethane resin or an epoxy resin.
 4. The polish pad according to claim 1, wherein the unfoamed segments and the foamed segments are disposed so that a polish object moves over the foamed segments and the unfoamed segments alternately during a polish process of the polish object.
 5. The polish pad according to claim 1, wherein each of the independent pores has a diameter equal to or less than 300 μm.
 6. The polish pad according to claim 1, wherein each of the foamed segments has a minor axis equal to or greater than 1 mm.
 7. The polish pad according to claim 1, wherein each of the unfoamed segments has a minor axis ranging from 1 mm to 10 cm.
 8. The polish pad according to claim 1, wherein the foamed segments and the unfoamed segments are exposed alternately in an upper surface of the polish pad in plan view.
 9. The polish pad according to claim 1, further comprising a cushion layer in intimate contact with an under surface of the polish layer.
 10. The polish pad according to claim 9, wherein the cushion layer comprises a soft polyurethane foam, or a soft polyethylene foam, or a soft unwoven fabric.
 11. The polish pad according to claim 1, wherein the unfoamed segment extends from an upper surface side of the polish layer to an under surface side of the polish layer in at least a portion of the polish layer in plan view.
 12. The polish pad according to claim 11, wherein the unfoamed segments are disposed in a lattice arrangement and the foamed segments are embedded between the unfoamed segments.
 13. The polish pad according to claim 11, wherein the unfoamed segments are disposed in isolated dots and the foamed segments are embedded between the unfoamed segments.
 14. The polish pad according to claim 11, wherein the polish layer includes a pattern on a surface thereof, the pattern being used for supplying and retaining slurry and comprising a trench or a through hole.
 15. The polish pad according to claim 11, wherein the polish layer includes a pattern on a surface thereof, the pattern being used for supplying and retaining slurry and being different from a layout pattern of the unfoamed segment and foamed segment.
 16. A method of polishing a surface of a polish object using the polish pad of claim
 1. 17. A method of manufacturing a polish pad comprising: forming foamed pellets including independent pores and unfoamed pellets free of independent pores with the same raw resin; and thermally molding a mixture of the foamed pellets and the unfoamed pellets to obtain a structurally integral composite mold including foamed segments and unfoamed segments.
 18. The method according to claim 17, wherein the independent pores are introduced into the foamed segments when the foamed pellets are thermally molded.
 19. A method of manufacturing a polish pad comprising: forming foamed raw resin including independent pores and unfoamed raw resin free of independent pores with the same raw resin; forming a homogenous mold including trenches by using either of the foamed raw resin and unfoamed raw resin; and introducing either of the foamed raw resin and unfoamed raw resin which was not used in forming the homogenous mold to the homogenous mold to form a structurally integral composite mold.
 20. The method according to claim 19, wherein after forming the composite mold, polishing and/or cutting the upper surface and the under surface of the composite mold to that the foamed segments and the unfoamed segments are exposed alternately at least in the upper surface of the composite mold. 